Surgical Device with Anti-Binding Features

ABSTRACT

Methods and devices are provided for preventing binding between components of a drive assembly of a surgical device. In an exemplary embodiment, a surgical device is provided having a ball-and-socket joint that allows bending of various drive shafts relative to the handle without causing movement of a drive rack disposed within the handle. Since the drive rack does not move in response to bending of the shaft, the drive gear and rack will remain aligned thus preventing jamming of the device.

FIELD

Surgical devices and methods having anti-binding features are provided.

BACKGROUND

Endoscopic surgical instruments are often preferred over traditionalopen surgical devices since a smaller incision, or incisions, associatedwith endoscopic surgical techniques tends to reduce the post-operativerecovery time and complications. Consequently, significant developmenthas gone into a range of endoscopic surgical instruments that aresuitable for precise placement of a distal end effector at a desiredsurgical site through a cannula of a trocar. These distal end effectorsengage the tissue in a number of ways to achieve a diagnostic ortherapeutic effect (e.g., endocutter, grasper, cutter, staplers, clipapplier, access device, drug/ gene therapy delivery device, and energydevice using ultrasound, RF, laser, etc.).

Endoscopic devices are passed through an access port, such as a trocar,to allow the distal end effector to engage tissue within a body cavityof a patient. The tissue can also be cut using a cutting element, suchas a knife. Loading forces experienced by a shaft of the device as theend effector engages the tissue may cause the shaft to bend relative tothe handle and to thus result in jamming or binding between componentsparticipating in distal advancement and proximal return of the cuttingelement. As a result, the cutting element can be prevented from beingproperly used to cut tissue. As another undesirable consequence, if thebinding occurs during advancement or retraction of the cuttinginstrument, the device cannot be removed because the cutting elementcannot be properly returned to its default position. The surgeon may beforced to open up the patient and manipulate the instrument, potentiallycausing serious harm to the patient.

Accordingly, there remains a need for methods and devices for preventingbinding of components of a cutting assembly of a surgical device.

SUMMARY

Various methods and devices are provided for preventing binding orjamming of components of a cutting assembly of a surgical device.

In one aspect, a surgical device is provided that includes a handle, anend effector, a closure tube, a knife pusher shaft, and a rack. Thehandle has an elongate shaft extending distally therefrom. The endeffector is disposed at a distal end of the elongate shaft and has firstand second jaws that are movable between an open configuration and aclosed configuration in which the first and second jaws are configuredto engage tissue therebetween. The closure tube extends through thehandle and the elongate shaft and is configured to move the first andsecond jaws between the open configuration and the closed configuration.The knife pusher shaft is disposed at least partially around the closuretube and is configured to move a cutting element through the first andsecond jaws for cutting tissue engaged therebetween. The rack is coupledto the knife pusher shaft by a ball-and-socket joint such that the knifepusher shaft can pivot relative to the rack. Movement of the rack iseffective to drive the knife pusher shaft and thereby move the cuttingelement through the first and second jaws.

The surgical device can vary in any number of ways. For example, thesurgical device can include a gear disposed within the handle andengaged with the rack for driving the rack. In one embodiment, thehandle can include a motorized drive assembly that is effective torotate the gear. The rack can have various configurations, for example,it be formed along an external surface of an elongate housing having acylindrical cavity formed therethrough that receives the closure tube.In such an example, the ball-and-socket joint can include a sphericalcavity formed in a distal end of the elongate housing, and a sphericalball formed on a proximal end of the knife pusher shaft and pivotallyseated within the spherical cavity.

The housing can also have various configurations, and in one embodimentit includes a stationary handle and a movable handle that is configuredto pivot toward the stationary handle to move the closure tubeproximally and thereby move the first and second jaws to the closedconfiguration.

In another aspect, a surgical device is provided that includes a handle,a jaw closure assembly, and a cutting assembly. The handle can have anelongate shaft extending distally therefrom and an end effector locatedon a distal end of the elongate shaft. The end effector can includefirst and second jaws that are movable between an open configuration anda closed configuration in which the first and second jaws are configuredto engage tissue therebetween. The jaw closure assembly can extendthrough the handle and the elongate shaft and it can be configured tomove the first and second jaws between the open and closed positions.The cutting assembly can extend through the handle and the elongateshaft and it can have a gear and a rack configured to drive a cuttingelement through the first and second jaws to cut tissue engaged betweenthe jaws. The cutting assembly can also include a ball-and-socket jointlocated within the handle that prevents binding between the gear andrack.

The surgical device can vary in any number of ways. For example, thecutting assembly can include a knife pusher tube having a ball formed ona proximal end thereof, and the rack can be formed on a housing having asocket formed therein that seats the ball. In another example, the jawclosure assembly can include a closure tube extending through the handleand the elongate shaft and it can be configured to move the first andsecond jaws between the open configuration and the closed configuration.The closure tube can extend through the knife pusher tube and thehousing. In one embodiment, the surgical device can include a motorizeddrive assembly disposed within the handle and effective to rotate thegear.

Methods for treating tissue are also provided. In one embodiment, themethod includes engaging tissue between first and second jaws of an endeffector on a distal end of an elongate shaft of a surgical device, andmanipulating the surgical device to move the tissue. A force applied tothe elongate shaft causes a knife pusher shaft extending therethrough topivot about a pivot joint relative to a rack housing disposed within thehandle. In one embodiment, the pivot joint is a ball-and-socket jointformed between the knife pusher shaft and the rack housing.

The method can vary in any number of ways. For example, the method canfurther include activating the surgical device to rotate a gear withinthe device such that the gear drives the rack housing and the knifepusher coupled thereto to move a cutting element through the first andsecond jaws and thereby cut the tissue engaged therebetween. In oneembodiment, the surgical device can include a motor, and activating thedevice can cause a power source to deliver energy to the motor such thatthe motor drives the gear.

In other aspects, engaging tissue between the first and second jaws caninclude moving a movable handle toward a stationary handle to move a jawclosure shaft proximally. Proximal movement of the jaw closure shaft cancause the first and second jaws to approximate to engage the tissue. Thejaw closure shaft can move proximally through the knife pusher shaft andthe rack housing when the movable handle is moved toward the stationaryhandle.

BRIEF DESCRIPTION OF DRAWINGS

The embodiments described above will be more fully understood from thefollowing detailed description taken in conjunction with theaccompanying drawings. The drawings are not intended to be drawn toscale. For purposes of clarity, not every component may be labeled inevery drawing. In the drawings:

FIG. 1 is a side view of one embodiment of a surgical device;

FIG. 2 is a side view of a handle portion of the surgical device of FIG.1, with various components removed for clarity;

FIG. 3 is a side, partially transparent view of various components ofthe surgical device of FIGS. 1 and 2;

FIG. 4 is a side view of a ball-and-socket joint and a gear of thesurgical device of FIGS. 1 and 2;

FIG. 5 is a perspective, transparent view of the ball-and-socket jointof FIG. 4;

FIG. 6 is a side view of the ball-and-socket joint of FIG. 5;

FIG. 7 is a perspective view of a knife pusher tube of the surgicaldevice of FIGS. 1 and 2; and

FIG. 8 is a perspective view of a rack housing of the surgical device ofFIGS. 1 and 2.

DETAILED DESCRIPTION

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the devices and methods disclosed herein. One ormore examples of these embodiments are illustrated in the accompanyingdrawings. Those skilled in the art will understand that the devices andmethods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary embodiments and thatthe scope of the present invention is defined solely by the claims. Thefeatures illustrated or described in connection with one exemplaryembodiment may be combined with the features of other embodiments. Suchmodifications and variations are intended to be included within thescope of the present invention.

Further, in the present disclosure, like-named components of theembodiments generally have similar features, and thus within aparticular embodiment each feature of each like-named component is notnecessarily fully elaborated upon. Additionally, to the extent thatlinear or circular dimensions are used in the description of thedisclosed systems, devices, and methods, such dimensions are notintended to limit the types of shapes that can be used in conjunctionwith such systems, devices, and methods. A person skilled in the artwill recognize that an equivalent to such linear and circular dimensionscan easily be determined for any geometric shape. Sizes and shapes ofthe systems and devices, and the components thereof, can depend at leaston the anatomy of the subject in which the systems and devices will beused, the size and shape of components with which the systems anddevices will be used, and the methods and procedures in which thesystems and devices will be used.

Various exemplary methods and devices are provided for preventingbinding or jamming of components of a drive assembly of a surgicaldevice due to load on a shaft of the device. In an exemplary embodiment,the surgical has a handle with an elongate shaft extending distallytherefrom and an end effector located on a distal end of the elongateshaft. The end effector includes first and second jaws that are movablebetween an open configuration and a closed configuration in which thefirst and second jaws are configured to engage tissue therebetween. Thesurgical device also includes, among other components, a cuttingassembly extending through the handle and the elongate shaft and havinga gear and a rack housing configured to drive a cutting element throughthe jaws to cut tissue engaged between the jaws. In an exemplaryembodiment, the cutting assembly includes a ball-and-socket jointlocated within the handle that prevents binding between the gear and therack. Thus, components of the cutting assembly are not affected bypossible bending of the elongate shaft of the surgical instrument due toload applied thereto in various surgical environments. This allows forproper advancement of the cutting element to cut tissue engaged betweenthe jaws. Furthermore, the ball-and-socket joint configuration allowsthe cutting element to be properly retracted after it is used to cut thetissue.

FIGS. 1 and 2 illustrate one embodiment of a surgical device configuredto grasp and cut tissue. As shown, the illustrated surgical device 100generally includes a proximal handle 10, a shaft 12 extending distallyfrom the proximal handle 10, and an end effector 14 for grasping tissue.The proximal handle 10 can be any type of pistol-grip, scissor grip,pencil-grip, or other type of handle known in the art that is configuredto carry various actuators, such as actuator levers, knobs, triggers, orsliders, for actuating various functions such as rotating, articulating,approximating, and/or firing the end effector 14. In the illustratedembodiment, the proximal handle 10 includes a stationary handle 22 and aclosure actuator 20 in the form of a handle that is movable toward andaway from the stationary handle 22 to open and close the jaws of the endeffector 14. The illustrated proximal handle 10 also includes a rotationknob 15 that is configured to rotate the shaft 12, a firing actuator 24that is configured to drive a cutting element through the end effector,and an energy actuator 26 that is configured to cause energy to bedelivered to tissue engaged between the jaws of the end effector 14. Thevarious actuators can be coupled to the end effector by one or moredrive assembly extending through the handle and through the elongateshaft 12.

The end effector can have a variety of sizes, shapes, andconfigurations. As shown in FIG. 1, the end effector 14 includes afirst, upper jaw 16 a in the form of an anvil and a second, lower jaw 16b that houses a staple cartridge with staples. The jaws are disposed ata distal end 12 d of the shaft 12. The jaws 16 a, 16 b are movablebetween an open position in which the jaws 16 a, 16 b are spaced adistance apart, and a closed position in which the jaws 16 a, 16 b aremoved toward one another and are substantially opposed. When the jaws 16a, 16 b are in the closed position, a longitudinal axis of the upper jaw16 a can be substantially parallel to a longitudinal axis of the lowerjaw 16 b and the jaws 16 a, 16 b can be in direct contact for engagingtissue therebetween. In the illustrated embodiment, the upper jaw 16 apivots relative to the shaft 12 and relative to the lower jaw 16 b whilethe lower jaw 16 b remains stationary, however in other embodiments thelower jaw can pivot relative to the upper stationary jaw, or both jawscan pivot. While the illustrated jaws 16 a, 16 b have a substantiallyelongate and straight shape, a person skilled in the art will appreciatethat one or both of the jaws 16 a, 16 b can be curved and/or can extendin various directions. The jaws 16 a, 16 b can have any suitable axiallength for engaging tissue, and the length can be selected based on thetargeted anatomical structure for transection and/or sealing.

As indicated above, the surgical device 100 has a stationary handle 22that is configured to open and close the jaws 16 a, 16 b of the endeffector 14. Manipulation of the closure actuator 20 can pivot orotherwise move the jaws relative to one another such that the jaws canengage tissue, move anatomical structures, or perform other surgicalfunctions. The closure actuator 20 can have various sizes, shapes, andconfigurations, but in the illustrated embodiment the closure actuator20 pivots about a pivot point to move toward and away from stationaryhandle 22. In particular, the closure actuator 20 can have a firstposition in which it is angularly offset and spaced apart from thestationary handle 22. In this position, as shown in FIG. 1, the jaws 16a, 16 b of the end effector 14 are open. The closure actuator 20 canhave a second position where it is positioned adjacent to, orsubstantially in contact with, the stationary handle 22. In thisposition, the jaws 16 a, 16 b of the end effector 14 are approximated tothe closed position to engage tissue and apply a force to tissuedisposed therebetween. The closure actuator 20 can be biased to thefirst open position with the jaws 16 a, 16 b of the end effector 14being open, as shown in FIG. 1. The closure actuator 20 can also includea locking mechanism for maintaining the closure actuator 20 in thesecond position. As shown in FIG. 2, the stationary handle includes alocking element 23 that is configured to engage a locking feature 21 onthe closure actuator 20 to lock the closure actuator 20 relative to thestationary handle 22. The illustrated locking mechanism is configured toautomatically engage when the closure actuator 20 substantially contactsthe stationary handle 22, however, in other embodiments, the lockingmechanism can automatically engage at each position the closure actuator20 is pivoted through, such as via ratcheting.

In order to effect closing of the jaws, the closure actuator 20 can becoupled to a drive assembly that is operatively associated with the jawsto move the jaws between the open and closed positions. In theembodiment shown in FIG. 2, the closure actuator 20 is coupled to a yoke236 via a linkage 238. The yoke 236 in turn is coupled to a jaw closuretube 216, that extends through the handle 10 and the elongate shaft 12and that is coupled to the first jaw 16 a. Movement of the closureactuator 20 toward the stationary handle 22 will move the linkage 238and thus the yoke 236 proximally, thereby moving the closure tube 216proximally. The closure tube 216 will in turn pull the proximal end ofthe first jaw 16 a to cause the jaw to move to the closed position. Thelocking mechanism will maintain the closure actuator 20 in the secondconfiguration adjacent to the stationary handle 22. A person skilled inthe art will appreciate that the drive assembly can have a variety ofother configurations and various drive mechanisms, including a drivescrew, motorized drive assemblies, other gears configurations, etc., canbe used.

As also indicated above, the surgical device 100 has a cutting assemblythat includes a firing actuator 24 that is configured to advance acutting element through the jaws 16 a, 16 b to cut tissue engagedtherebetween. The firing actuator 24 can have various sizes, shapes, andconfigurations, but in the illustrated embodiment it is in the form of abutton or trigger that can be depressed and move proximally into thehousing. In another embodiment, the firing actuator 24 can be in theform of a switch, lever, etc., that can be slid, pivoted, or otherwisemoved by a user. Depressing or pivoting the firing actuator 24 can causea cutting assembly to advance through the end effector. As shown in FIG.2, the firing actuator 24 has a cut-out formed therein and defining afiring rack 229. The firing rack 229 is coupled to a gear 230 via one ormore additional gears. Gear 230 has teeth formed thereon that threadablyengage a toothed drive rack 232 that is formed on an elongate rackhousing 234. When the firing actuator 24 is pivoted proximally, thefiring rack 229 drives the gear 230 (via one or more additional gears),and rotation of the gear 230 drives the rack housing 234 distally.

Advancement of the rack housing 234 drives a cutting assembly throughthe first and second jaws to cut tissue engaged between the jaws. Whilethe cutting assembly can have various configurations, as shown in moredetail in FIG. 3, the cutting assembly generally includes a knife pushershaft 218 that is coupled at its proximal end to the rack housing 234and at its distal end to a cutting element. The knife pusher shaft 218is generally in the form of an elongate hollow shaft having the jawclosure tube 216 extending therethrough. As shown in FIG. 3, the jawclosure tube 216 extends proximally beyond the knife pusher shaft 218,through the rack housing 234, and proximally beyond the rack housing 234to couple to the yoke 236 that is driven by the closure actuator 20 viathe linkage 238.

The cutting element or knife 242 can have any suitable configuration fortransecting tissue captured between the jaws, and it can be sized andshaped to transect or cut various thicknesses and types of tissue. In anexemplary embodiment, the cutting assembly includes a cutting elementhaving a sharp or serrated edge configured to transect the tissue. Insome embodiments, the cutting assembly can include, for example, anE-beam compression member that travels through slots formed in each jawto pull the jaws into a parallel orientation and to compress tissuetherebetween. The cutting element can be coupled to or integrally formedon the compression member. In other embodiments, the cutting assemblycan include a shaft having a knife blade that is not attached to acompression member such that the cutting assembly can advance andretract relative to the jaws without applying compression to the tissue.

As further noted above, the device 100 can also include a third actuatorin the form of an energy actuator 26 that is effective to cause energyto be delivered to tissue engaged between the jaws. The energy actuator26 can be configured to operatively couple to a generator, which can bea separate unit that is electrically connected to the surgical device100. The energy actuator 26 and the generator can be operatively coupledso that the device is configured to apply energy to tissue engaged bythe end effector when the energy actuator 26 is activated. The generatorcan be any suitable generator known in the art, such as an RF generator,an ultrasound generator, or other type of a generator. A lumen (notshown) of the shaft 12 can carry electrical leads or wires that candeliver electrical energy to components of the end effector 14.

While not shown, a person skilled in the art will appreciate that thejaw closing assembly and/or the cutting assembly can be powered ratherthan being manually driven. For example, the closure actuator can becoupled to a motor disposed in the proximal handle 10 and manualmovement of the closure actuator 20 can cause a processor to send acontrol signal to the motor, which can interact with various gears orother components to cause the jaws 16 a, 16 b to open and close. By wayof further example, the firing actuator 24 can be in electricalcommunication with a motor disposed in the proximal handle 10 andactivation of the firing actuator 24 can similarly activate the motorwhich can be operatively coupled to one or more gears and a rack fordriving a cutting element through the jaws. Energy delivery can likewisebe controlled by a processor that controls the closure and/or firingsystems. The device can also include other power-driven features, suchas powered articulation and/or powered rotation of the end effectorand/or shaft.

In an exemplary embodiment, the device 100 includes features thatprevent binding of components of the cutting assembly. In particular,during use of the end effector to engage and manipulate tissue, a loadis often applied to the elongate shaft 12 that can cause the elongateshaft 12 to bend or pivot relative to the handle 10. A person skilled inthe art will appreciate that the term “bend” is used herein to refer tomovement out of the longitudinal axis, including pivotal movement orflexion that causes various portions of the component to be misalignedwith respect to its longitudinal axis. Since the jaw closure tube 216extends through the rack housing 234 and through at least a portion ofthe knife pusher shaft 218, any bending of the elongate shaft 12, andthus the jaw closure tube 216 and knife pusher shaft 218 extendingtherethrough, will cause the rack housing 234 to bend or pivot out ofaxis. As a result, the drive rack 232 on the rack housing 234 willbecome misaligned with respect to the gear 230, thereby potentiallyresulting in jamming or binding of the gears. When the gear 230 isjammed or misaligned with the drive rack 232 on the rack housing 234,the firing actuator 24 will be prevented from driving the cuttingelement.

Accordingly, in an exemplary embodiment, the device 100 includesfeatures to prevent such binding or jamming from occurring.Specifically, the knife pusher shaft 218 can be configured such that thebending of the knife pusher shaft 218 and the closure tube 216 disposedtherein does not cause the rack housing 234 to bend or otherwise moveout of axis. As shown in FIGS. 2-6, the knife pusher shaft 218 iscoupled to the rack housing 234 by a ball-and-socket joint 250 such thatthe knife pusher shaft 218 can pivot or angulate relative to the rackhousing 234. In this way, in the event the elongate shaft 12 of thesurgical device 100 bends or otherwise moves, the rack housing 234 doesnot bend or move with it. The drive rack 232 and the gear 230 thereforeremain in alignment.

FIGS. 4-8 illustrate the components of the ball-and-socket joint 250 inmore detail. As shown, the ball-and-socket joint 250 includes aspherical socket or spherical cavity 252 formed in a distal end 234 d ofthe elongate rack housing 234 having the drive rack 232 formed on anexternal surface thereof, and a spherical ball 254 formed on a proximalend 218 p of the knife pusher shaft 218. As shown in FIGS. 5 and 6, thespherical ball 254 is pivotally seated within the spherical cavity 252such that the knife pusher shaft 218 can pivot or angulate relative tothe rack housing 234.

FIG. 7 illustrates the spherical ball 254 on the knife pusher shaft 218in more detail. As shown, the knife pusher shaft 218 has a generallyelongate cylindrical or semi-cylindrical configuration such that theknife pusher shaft 218 is disposed at least partially around the closuretube 216. While not shown, the distal portion of the knife pusher shaftcan be in the form of a fully enclosed cylindrical tube. The sphericalball 254 is formed on the proximal end 218 p of the knife pusher shaft218 and is fully cannulated to receive the closure tube 216therethrough. In the illustrated embodiment, the spherical ball 254 isintegrally formed with the knife pusher shaft 218. However, it will beappreciated that the spherical ball 254 can be formed on the knifepusher shaft 218 in any suitable manner, for example, it can be coupledto the knife pusher shaft 218.

The rack housing 234 is shown in more detail in FIG. 8. The drive rack232 is formed along an external bottom surface 260 of the rack housing234 such that the drive rack 232 faces and engages with the gear (e.g.,gear 230 in FIGS. 2-4). The rack housing 234 has a generally elongaterectangular configuration with an elongate cavity 262 formedtherethrough that receives the closure tube 216. The closure tube 216thus extends through the knife pusher shaft 218 and the rack housing234, as shown in FIGS. 5 and 6.

The spherical ball 254 formed on the proximal end 218 p of the knifepusher shaft 218 and the spherical cavity 252 formed in the distal end234 d of the rack housing 234 can have any suitable size, but preferablythe size is configured to allow free rotation of the knife pusher shaft218 relative to the rack housing 234. The spherical cavity 252 can beformed on an inner wall of the cavity 262 in the rack housing 234 byforming concave seating surfaces within the inner wall, as shown inFIGS. 6 and 8. The spherical cavity 252 is sized and shaped to pivotallyreceive therein the spherical ball 254.

The spherical cavity 252 and the spherical ball 254 of theball-and-socket joint 250 are configured such that the knife pushershaft 218 can be disposed at various angles with respect to the rackhousing. At the same time, the fit between the knife pusher shaft 218and the drive rack 232 can be sufficiently tight, without a slack. Theconfiguration of the ball-and-socket joint 250 allows the knife pushershaft 218 and the closure tube 216 to bend without affecting a positionof the rack housing 234. In this way, because the drive rack 232 and thegear 230 remain aligned, the gear 230 can drive the drive rack 232 topush the knife pusher shaft 218 as intended. Bending of the knife pushershaft 218 and the closure tube 216 does not affect the movement of therack housing 234.

The devices disclosed herein can be designed to be disposed of after asingle use, or they can be designed to be used multiple times. In eithercase, however, the device can be reconditioned for reuse after at leastone use. Reconditioning can include any combination of the steps ofdisassembly of the device, followed by cleaning or replacement ofparticular pieces, and subsequent reassembly. In particular, the devicecan be disassembled, and any number of the particular pieces or parts ofthe device can be selectively replaced or removed in any combination.Upon cleaning and/or replacement of particular parts, the device can bereassembled for subsequent use either at a reconditioning facility, orby a surgical team immediately prior to a surgical procedure. Thoseskilled in the art will appreciate that reconditioning of a device canutilize a variety of techniques for disassembly, cleaning/replacement,and reassembly. Use of such techniques, and the resulting reconditioneddevice, are all within the scope of the present application.

Preferably, the devices and components described herein will beprocessed before use. First, a new or used instrument is obtained and ifnecessary cleaned. The instrument can then be sterilized. In onesterilization technique, the instrument is placed in a closed and sealedcontainer, such as a plastic or TYVEK bag. The container and instrumentare then placed in a field of radiation that can penetrate thecontainer, such as gamma radiation, x-rays, or high-energy electrons.The radiation kills bacteria on the instrument and in the container. Thesterilized instrument can then be stored in the sterile container. Thesealed container keeps the instrument sterile until it is opened in themedical facility.

It is preferred that device is sterilized. This can be done by anynumber of ways known to those skilled in the art including beta or gammaradiation, ethylene oxide, steam, and a liquid bath (e.g., cold soak).An exemplary embodiment of sterilizing a device including internalcircuitry is described in more detail in U.S. Pat. Pub. No. 2009/0202387filed Feb. 8, 2008 and entitled “System And Method Of Sterilizing AnImplantable Medical Device.” It is preferred that device, if implanted,is hermetically sealed. This can be done by any number of ways known tothose skilled in the art.

One skilled in the art will appreciate further features and advantagesof the described devices and methods based on the above-describedembodiments. Accordingly, the present disclosure is not to be limited bywhat has been particularly shown and described, except as indicated bythe appended claims. All publications and references cited herein areexpressly incorporated herein by reference in their entirety.

What is claimed is:
 1. A surgical device, comprising: a handle having anelongate shaft extending distally therefrom; an end effector at a distalend of the elongate shaft and having first and second jaws that aremovable between an open configuration and a closed configuration inwhich the first and second jaws are configured to engage tissuetherebetween; a closure tube extending through the handle and theelongate shaft and configured to move the first and second jaws betweenthe open configuration and the closed configuration; a knife pushershaft disposed at least partially around the closure tube and configuredto move a cutting element through the first and second jaws for cuttingtissue engaged therebetween; and a rack coupled to the knife pushershaft by a ball-and-socket joint such that the knife pusher shaft canpivot relative to the rack, wherein movement of the rack is effective todrive the knife pusher shaft and thereby move the cutting elementthrough the first and second jaws.
 2. The device of claim 1, furthercomprising a gear disposed within the handle and engaged with the rackfor driving the rack.
 3. The device of claim 1, wherein the rack isformed along an external surface of an elongate housing having acylindrical cavity formed therethrough that receives the closure tube.4. The device of claim 3, wherein the ball-and-socket joint comprises aspherical cavity formed in a distal end of the elongate housing, and aspherical ball formed on a proximal end of the knife pusher shaft andpivotally seated within the spherical cavity.
 5. The device of claim 1,wherein the housing includes a stationary handle and a movable handlethat is configured to pivot toward the stationary handle to move theclosure tube proximally and thereby move the first and second jaws tothe closed configuration.
 6. A surgical device, comprising: a handlehaving an elongate shaft extending distally therefrom and an endeffector located on a distal end of the elongate shaft, the end effectorincluding first and second jaws that are movable between an openconfiguration and a closed configuration in which the first and secondjaws are configured to engage tissue therebetween; a jaw closureassembly extending through the handle and the elongate shaft andconfigured to move the first and second jaws between the open and closedpositions; and a cutting assembly extending through the handle and theelongate shaft and having a gear and a rack configured to drive acutting element through the first and second jaws to cut tissue engagedbetween the jaws, wherein the cutting assembly includes aball-and-socket joint located within the handle that prevents bindingbetween the gear and rack.
 7. The surgical device of claim 6, whereinthe cutting assembly includes a knife pusher tube having a ball formedon a proximal end thereof, and wherein the rack is formed on a housinghaving a socket formed therein that seats the ball.
 8. The surgicaldevice of claim 7, wherein the jaw closure assembly includes a closuretube extending through the handle and the elongate shaft and configuredto move the first and second jaws between the open configuration and theclosed configuration, the closure tube extending through the knifepusher tube and the housing.
 9. A method for treating tissue,comprising: engaging tissue between first and second jaws of an endeffector on a distal end of an elongate shaft of a surgical device; andmanipulating the surgical device to move the tissue, wherein a forceapplied to the elongate shaft causes a knife pusher shaft extendingtherethrough to pivot about a pivot joint relative to a rack housingdisposed within the handle.
 10. The method of claim 9, wherein the pivotjoint comprises a ball-and-socket joint formed between the knife pushershaft and the rack housing.
 11. The method of claim 9, furthercomprising activating the surgical device to rotate a gear within thedevice, the gear driving the rack housing and the knife pusher coupledthereto to move a cutting element through the first and second jaws andthereby cut the tissue engaged therebetween.
 12. The method of claim 9,wherein engaging tissue between the first and second jaws comprisingmoving a movable handle toward a stationary handle to move a jaw closureshaft proximally, the proximal movement of the jaw closure shaft causingthe first and second jaws to approximate to engage the tissue.
 13. Themethod of claim 12, wherein the jaw closure shaft moves proximallythrough the knife pusher shaft and the rack housing when the movablehandle is moved toward the stationary handle.